Characterization of Triadica sebifera (L.) Small Extracts, Antifeedant Activities of Extracts, Fractions, Seed Oil and Isolated Compounds against Plutella xylostella (L.) and Their Effect on Detoxification Enzymes.

Plutella xylostella L. is one of the world's major pests of cruciferous crops. The indiscriminate use of synthetic insecticides has led to insecticide resistance and resurgence, and has been harmful to non-target organisms and the environment. Botanical insecticides are the best alternatives to synthetic pesticides for the management of pests in organic agriculture and integrated management. T. sebifera is an invasive species and has good potential as an insecticide due to the availability of plant material in some parts of India. The antifeedant activities of T. sebifera have not been reported against P. xylostella and other lepidopteron insects to date. Therefore, the current study targeted the characterization of leaf and bark extracts, feeding deterrence, synergistic and detoxification enzyme activities of leaf/bark ethanolic extracts/fractions, seed oil, and isolated compounds. UHPLC-QTOF-IMS analysis showed that shikimic acid, xanthoxylin, quercetin, kaempferol, methyl gallate, and stigmasterol are common metabolites identified in leaf and bark extracts. The combination of seed oil with bark extract showed higher deterrence (DC50 = 317.10 mg/L) as compared to leaf/bark extracts alone. Gallic acid showed higher deterrence (67.48%) than kaempferol and quercetin. The n-butanol fraction of bark was more repellent (RC50 = 414.61 mg/L). Based on DC50, the seed oil with leaf extract (1:1 ratio) alone with choice and seed oil with leaf and bark extract without choice showed synergistic interaction, but seed oil with bark extract with choice showed additive interaction. The ethanol extract of leaf, bark, and seed oil inhibited GST and AChE in P. xylostella. The leaf extract and seed oil or their combinations may be recommended as antifeedants to reduce damage by P. xylostella based on persistence, antifeedant, phytotoxicity, safety to predators/parasitoids, etc., under field conditions.

Chemical Composition, Insecticidal, Persistence and Detoxification Enzyme Inhibition Activities of Essential Oil of Artemisia maritima against the Pulse Beetle.

Pulse beetle is the major pests of pulses that cause significant loss to grains leads to unfit for consumption and marketing. Indiscriminate use of synthetic pesticides for the control of pulse beetle (Callosobruchus chinensis and Callosobruchus maculatus) led to insect resistance, pesticide residues on grains which affect consumer's health and environment. Essential oils (EOs) are good alternatives to synthetics due to their safety to the environment and consumers' health. The main objective of the present study was to explore the chemical composition, fumigant, repellency, ovipositional deterrence, persistence, and detoxification enzyme inhibition of Artemisia maritima essential oil against pulse beetle. Results showed that primary components of the EO were 1,8-Cineole and bornyl acetate. EO showed promising fumigant toxicity to C. chinensis and C. maculatus (LC50 = 1.17 and 0.56 mg/L, respectively) after 48 h. In the repellent assay, EO at 8 mg/L showed 92-96% repellence after 1 h. In ovipositional deterrence assay, EO showed more ovipositional deterrence against C. chinensis (OD50 = 3.30 mg/L) than C. maculatus (OD50 = 4.01 mg/L). Higher concentrations of oil (8 and 6 mg/L) in C. maculatus showed significant inhibition of the glutathione-S-transferase enzyme (7.14 and 5.61 n mol/min/mL, respectively).

Insecticidal and Enzyme Inhibition Activities of Leaf/Bark Extracts, Fractions, Seed Oil and Isolated Compounds from Triadica sebifera (L.) Small against Aphis craccivora Koch.

Aphid, Aphis craccivora Koch (Hemiptera: Aphididae), is a major sap-sucking insect pest of leguminous crops and also transmits plant viruses, leading to economic yield loss. Indiscriminate and repeated use of insecticides for control of aphid leads to the development of resistance, and is harmful to the environment, non-target organisms, etc. Plant-based extracts/seed oils (SO) are the best alternatives to insecticides. Insecticidal activities of Triadica sebifera have not been reported against A. craccivora and other insect pests to date. In the current study, the main objective was to study the insecticidal activities of leaf/bark extracts/fractions, seed oil, isolated compounds, and their combinations against A. craccivora. Results showed that, among the extracts, ethanolic bark extract 80% (LC50 = 5115.98 mg/L) was more effective against A. craccivora. Among fractions, the n-hexane fraction of leaves (LC50 = 425.73 mg/L) and the ethyl acetate fraction of bark (LC50 = 813.45 mg/L) were promising. Among compounds, gallic acid was the most effective (LC50 = 1303.68 mg/L) compared to shikimic acid and quercetin. SO (LC50 = 850.94 mg/L) was superior compared to extracts/fractions/compounds. All the combinations showed toxicity and synergistic activity. Leaf/bark extracts and SO significantly inhibited the AChE and GST activity in A. craccivora. Based on field bio-efficacy, the leaf extract/SO or their combinations can be recommended for the control of aphids.

Insecticidal Activity of Extracts, Fractions, and Pure Molecules of Cissampelos pareira Linnaeus against Aphid, Aphis craccivora Koch.

Aphis craccivora Koch is a polyphagous and major pest of leguminous crops causing significant damage by reducing the yield. Repeated application of synthetic insecticides for the control of aphids has led to development of resistance. Therefore, the present study aimed to screen the insecticidal activity of root/stem extracts/fractions, and pure molecules from Cissampelos pareira Linnaeus against A. craccivora for identification of lead(s). Among root extract/fractions, the n-hexane fraction was found most effective (LC50 = 1828.19 mg/L) against A. craccivora, followed by parent extract (LC50 = 2211.54 mg/L). Among stem extract/fractions, the n-hexane fraction (LC50 = 1246.92 mg/L) was more effective than the water and n-butanol fractions. Based on GC and GC-MS analysis, among different compounds identified in the n-hexane fraction of root and stem, ethyl palmitate (known to possess insecticidal activity) was present in the highest concentration (24.94 to 52.95%) in both the fractions. Among pure molecules, pareirarineformate was found most effective (LC50 = 1491.93 mg/L) against A. craccivora, followed by cissamine (LC50 = 1556.31 mg/L). Parent extract and fractions of C. pareira possess promising activity against aphid. Further, field bio-efficacy studies are necessary to validate the current findings for the development of botanical formulation.

Chemical Composition and Insecticidal Activities of Essential Oils against the Pulse Beetle.

Pulse beetles, Callosobruchus chinensis and Callosobruchus maculatus, are essential pests of cowpea, gram, soybean and pulses. Application of synthetic insecticides against the pulse beetle has led to insect resistance; insecticide residues on grains affect human health and the environment. Essential oils (EOs) are the best alternatives to synthetics due to their safety to the environment and health. The main objective of the investigation was to study the chemical composition and insecticidal activities of EOs, their combinations and compounds against the pulse beetle under laboratory. Neo-isomenthol, carvone and ß-ocimene are the significant components of tested oils using GC-MS. Mentha spicata showed promising fumigant toxicity against C. chinensis (LC50 = 0.94 µL/mL) and was followed by M. piperita (LC50 = 0.98 µL/mL), whereas M. piperita (LC50 = 0.92 µL/mL) against C. maculatus. A combination of Tagetes minuta + M. piperita showed more toxicity against C. chinensis after 48 h (LC50 = 0.87 µL/mL) than T. minuta + M. spicata (LC50 = 1.07 µL/mL). L-Carvone showed fumigant toxicity against C. chinensis after 48 h (LC50 = 1.19 µL/mL). Binary mixtures of T. minuta +M. piperita and M. spicata showed promising toxicity and synergistic activity. EOs also exhibited repellence and ovipositional inhibition. The application of M. piperita can be recommended for the control of the pulse beetle.

Larvicidal activity and structure activity relationship of cinnamoyl amides from Zanthoxylum armatum and their synthetic analogues against diamondback moth, Plutella xylostella.

Cinnamoyl amides isolated from Zanthoxylum armatum (Rutaceae) and their synthetic analogues were tested for their insecticidal activity against the second instar larvae of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) to determine the promising structures with insecticidal activity. Most of the test compounds showed promising activity against larvae of P. xylostella. However, the activities of different compounds varied depending on the presence of different substituents at various positions of both the aromatic rings A and B. Among the tested compounds, 8, N-(3-bromo-4-methoxyphenethyl)cinnamamide showed best larvicidal activity with an LC50 = 62.13 mg/L followed by 6, N-(3׳-bromophenethyl)cinnamamide (LC50=128.49 mg/L) and 2 N-(4׳-methoxyphenylethyl)cinnamamide (LC50 = 225.65 mg/L).

Triterpenoid Saponins from Clematis graveolens and Evaluation of their Insecticidal Activities.

A new hederagenin based triterpenoid saponin, clematograveolenoside A (1), along with three known saponins, tomentoside A (2), huzhangoside D (3) and clematoside S (4), were isolated from the roots and rhizomes of Clematis graveolens. The structure of new compound was elucidated on the basis of detailed analysis of chemical and spectroscopic data including 1D- and 2D NMR spectra. Compound 2 was found the most effective against aphid (Aphis craccivora) with an LC50 of 1.2 and 0.5 mg/mL after treatment for 72 and 96 h, respectively and was followed by compound 4 (LC50 = 2.3 and 1.9 mg/mL) and 1 (LC50 = 3.2 and 2.6 mg/mL). In case of termite (Coptotermis homii), compound 1 was found more toxic with an LC50 of 0.1 mg/L after 24 h of treatment followed by compound 2, 3 and 4 (LC50 = 0.1, 0.2 and 0.2 mg/mL, respectively).